An automobile is equipped with a pair of suspension devices for left and right wheels and a stabilizer connecting the pair of suspensions. The stabilizer plays the following role. Specifically, for example, when the automobile turns and the vehicle body is inclined (roll phenomenon), the stabilizer exerts a spring action (elastic force for restoration from torsional deformation) utilizing the repulsive force generated by the torsion of a spring steel according to the deviation of the positions of the left and right wheels, thereby preventing the roll of the vehicle.
A stabilizer is a component including a stabilizer bar using a spring steel which is formed into a substantially U shape. Both end portions of the stabilizer bar having the substantially U shape are attached to suspension arms with connection rods, respectively. In addition, the center portion of the stabilizer bar is provided rotatably with respect to the vehicle body. Note that a rubber bush may be attached to at least a portion of the center portion of the stabilizer bar for the purposes of antivibration and the like. The rubber bush is adhesively fixed to a bracket, and the bracket is fixed to the vehicle body with bolts or the like.
Conventionally, the rubber bush is attached to the stabilizer bar not by adhesively fixing or the like, but by simply bringing the rubber bush onto the center portion of the stabilizer bar while the stabilizer bar is inserted through the rubber bush. However, mud, sand, salt water, or the like may enter the space between the stabilizer bar and the rubber bush, so that a coating film provided on the surface of the stabilizer bar may be broken, in some cases. When the coating film provided on the surface of the stabilizer bar is broken, problems may be caused such as corrosion of the stabilizer bar or even bending of the stabilizer bar due to the progress of the corrosion. Moreover, when water enters the space between the stabilizer bar and the rubber bush or when the atmospheric temperature is extremely low, problems may be caused such as noise generation due to slippage of the rubber bush on the stabilizer bar. To solve these problems, stabilizer bars to which rubber bushes are adhesively fixed with adhesive agents have been developed recently, and patent documents relating to these stabilizer bars have been disclosed (see, for example, Patent Documents 1 and 2).
Patent Document 1 discloses a stabilizer bar with rubber bush, in which a tubular rubber bush having a U-shaped outer peripheral surface and a straight line-shaped flat surface continuous to both ends of the U-shaped outer peripheral surface is fixed by being fitted to the outside of a fitted portion of the stabilizer bar. More specifically, as the stabilizer bar with rubber bush, Patent Document 1 discloses a stabilizer bar with rubber bush, wherein the rubber bush is formed by vulcanization such that a projecting and curved portion, whose outer peripheral surface is a projecting and curved surface of the U-shaped outer peripheral surface, of the rubber bush can take a state of bulging outwardly in the radial direction by a set amount relative to the dimension of the target product; the rubber bush is put on the outside of the fitted portion of the stabilizer bar on which a thermosetting adhesive agent is applied; and, with the rubber bush being compressed by pressing the projecting curved surface and the flat surface, the rubber bush is heated to be adhesively fixed to the fitted portion.
Patent Document 2 discloses a bush- and bracket-integrated stabilizer bar including a stabilizer bar, a rubber bush attached to an outer periphery of the stabilizer bar, and a bracket provided to an outer periphery of the rubber bush and configured to mount the stabilizer bar to a bottom portion of a vehicle body with the rubber bush, wherein the stabilizer bar includes an amine-based curable epoxy paint or an amine-containing cationic paint and a surface treatment layer containing a halogen donor-based surface treatment agent on the paint, the rubber bush includes a surface treatment layer containing a halogen donor-based surface treatment agent on an inner surface thereof, and an adhesive agent layer containing an amine-based or organic hydrazide-based curing agent and an epoxy resin is formed between the stabilizer bar and the rubber bush with each of the surface treatment layers intervened.